Gym 313459D

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long
#define db double

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N=105;
const db eps=1e-6;

inline db sqr(db x){
    return x*x;
}

inline int dcmp(const db &x){
    if(fabs(x)<eps)return 0;
    return x>0?1:-1;
}

struct Point{
    db x,y;

    inline Point(){}
    inline Point(db _x,db _y):x(_x),y(_y){}

};

#define Vec Point

inline Vec operator +(const Vec &a,const Vec &b){
    return Vec(a.x+b.x,a.y+b.y);
}

inline Vec operator -(const Vec &a,const Vec &b){
    return Vec(a.x-b.x,a.y-b.y);
}

inline void operator +=(Vec &a,const Vec &b){
    a.x+=b.x,a.y+=b.y;
}

inline void operator -=(Vec &a,const Vec &b){
    a.x-=b.x,a.y-=b.y;
}

inline Vec operator *(const Vec &a,const db &b){
    return Vec(a.x*b,a.y*b);
}

inline Vec operator /(const Vec &a,const db &b){
    return Vec(a.x/b,a.y/b);
}

inline db Norm(const Vec &a){
    return sqrt(sqr(a.x)+sqr(a.y));
}

inline Point Middle(const Point &A,const Point &B){
    return (A+B)/2;
}

inline Vec I(const Vec &a){
    return a/Norm(a);
}

inline db Dis(const Point &A,const Point &B){
    return Norm(A-B);
}

inline Vec Rotate(const Vec &A){
    return Vec(-A.y,A.x);
}


Point P[N];

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int R;r(R);
    int n;r(n);
    for(int i=0;i<n;++i){
        int x,y;r(x),r(y);
        P[i]=Point(x,y);
    }
    int ans=1;
    for(int i=0;i<n;++i){
        for(int j=i+1;j<n;++j){
            db tmp=Dis(P[i],P[j]);
            if(dcmp(tmp-2*R)>0)continue;
            Point M=Middle(P[i],P[j]);
            db len=sqrt(R*R-tmp*tmp/4);
            Point C=M+Rotate(I(P[i]-P[j]))*len;
            int cnt=0;
            for(int k=0;k<n;++k){
                if(dcmp(Dis(C,P[k])-R)<=0)cnt++;
                ans=max(ans,cnt);
            }
            C=M-Rotate(I(P[i]-P[j]))*len;
            cnt=0;
            for(int k=0;k<n;++k){
                if(dcmp(Dis(C,P[k])-R)<=0)cnt++;
                ans=max(ans,cnt);
            }
        }
    }
    printf("%d\n",ans);
    return 0;
}